Susceptibility of the Endangered Karner Blue Butterfly (Lepidoptera: Lycaenidae) to \u3ci\u3eBacillus Thuringiensis\u3c/i\u3e Var. \u3ci\u3eKurstaki\u3c/i\u3e Used for Gypsy Moth Suppression in Michigan

We investigated the phenological and physiological susceptibility of the endangered Karner blue butterfly (Lycaeides melissa samuelis) to Bacillus thuringiensis var. kurstaki (Bt), a product widely used for gypsy moth (Lymantria dispar) suppression in Michigan and other infested states. We monitored phenology of the bivoltine Karner blue in two regions of Michigan from 1993 to 1995 to determine if larval stages overlapped temporally with the period of Bt application for gypsy moth suppression. Karner blue larvae of the spring generation were found during the period that Bt was applied in nearby areas in 1993 only. However, spring-generation adults or newly laid eggs were observed up to 11 days before applications in 1994 and 1995. Since Karner blue eggs develop within one week, summer-generation larvae were most likely present during or shortly after 1994 and 1995 Bt application periods. These larvae would have been at risk, assuming Bt persistence of 4 to 6 days. Physiological susceptibility of Karner blue larvae to Bt was determined in a laboratory bioassay. Larvae were reared on wild lupine (Lupinus perennis) foliage that was untreated, or sprayed with Bt formulations at rates of 30-37 or 90 BIU/ha. A similar bioassay with second instar gypsy moth larvae on similarly treated white oak (Quercus alba) foliage was conducted concurrently. Karner blue survival was 100%, 27% and 14% on control, low and high Bt treatments, respectively. Early and late Karner blue instars were equally susceptible to Bt. Survival of gypsy moth was 80%, 33% and 5% on control, low and high Bt treatments, respectively, and did not differ significantly from Karner blue survival. We conclude that Karner blue is both phenologically and physiologically susceptible to Bt used for gypsy moth suppression, although the larval generation at risk and extent of phenological overlap may vary from year to year

Indian Bt cotton varieties do not affect the performance of cotton aphids.

Cotton varieties expressing Cry proteins derived from the soil bacterium Bacillus thuringiensis (Bt) are grown worldwide for the management of pest Lepidoptera. To prevent non-target pest outbreaks and to retain the biological control function provided by predators and parasitoids, the potential risk that Bt crops may pose to non-target arthropods is addressed prior to their commercialization. Aphids play an important role in agricultural systems since they serve as prey or host to a number of predators and parasitoids and their honeydew is an important energy source for several arthropods. To explore possible indirect effects of Bt crops we here examined the impact of Bt cotton on aphids and their honeydew. In climate chambers we assessed the performance of cotton aphids, Aphis gossypii Glover (Hemiptera: Aphididae) when grown on three Indian Bt (Cry1Ac) cotton varieties (MECH 12, MECH 162, MECH 184) and their non-transformed near isolines. Furthermore, we examined whether aphids pick up the Bt protein and analyzed the sugar composition of aphid honeydew to evaluate its suitability for honeydew-feeders. Plant transformation did not have any influence on aphid performance. However, some variation was observed among the three cotton varieties which might partly be explained by the variation in trichome density. None of the aphid samples contained Bt protein. As a consequence, natural enemies that feed on aphids are not exposed to the Cry protein. A significant difference in the sugar composition of aphid honeydew was detected among cotton varieties as well as between transformed and non-transformed plants. However, it is questionable if this variation is of ecological relevance, especially as honeydew is not the only sugar source parasitoids feed on in cotton fields. Our study allows the conclusion that Bt cotton poses a negligible risk for aphid antagonists and that aphids should remain under natural control in Bt cotton fields

A bounded jump for the bounded Turing degrees

We define the bounded jump of A by A^b = {x | Exists i <= x [phi_i (x) converges and Phi_x^[A|phi_i(x)](x) converges} and let A^[nb] denote the n-th bounded jump. We demonstrate several properties of the bounded jump, including that it is strictly increasing and order preserving on the bounded Turing (bT) degrees (also known as the weak truth-table degrees). We show that the bounded jump is related to the Ershov hierarchy. Indeed, for n > 1 we have X <=_[bT] 0^[nb] iff X is omega^n-c.e. iff X <=_1 0^[nb], extending the classical result that X <=_[bT] 0' iff X is omega-c.e. Finally, we prove that the analogue of Shoenfield inversion holds for the bounded jump on the bounded Turing degrees. That is, for every X such that 0^b <=_[bT] X <=_[bT] 0^[2b], there is a Y <=_[bT] 0^b such that Y^b =_[bT] X.Comment: 22 pages. Minor changes for publicatio

WHAT IS THE VALUE OF BT CORN?

A common perception is that the value of Bt corn arises from two components-Bt corn increases expected profit and reduces profit variability. This perception encourages farmers and the policy makers to add a risk benefit to estimates of the value of Bt corn to account for the variability reduction. However, a conceptual model generates a useful decomposition of the value of Bt corn and a condition determining the impact of Bt corn on profit variability. An empirical model finds that Bt corn increases profit variability and thus decreases the value of Bt corn by 10-25% depending on risk preferences.Crop Production/Industries,